####018004923#### FXUS64 KHUN 062250 AFDHUN Area Forecast Discussion National Weather Service Huntsville AL 450 PM CST Sat Dec 6 2025 ...New AVIATION... .KEY MESSAGES... Issued at 938 AM CST Sat Dec 6 2025 - Low to medium chances of fog tonight, with low to medium chances of freezing fog over northeast Alabama and southern middle Tennessee later tonight as temperatures drop to freezing or just below. - Low to medium (20-40%) chances of periodic light rain late Sunday afternoon through Monday morning. - Colder temperatures return early next week with sub-freezing lows Monday night, followed by a warming trend through midweek. && .NEAR TERM... (Tonight) Issued at 155 PM CST Sat Dec 6 2025 The low stratus cloud deck that blanketed the region this morning has been gradually eroding this afternoon. Skies should be mostly clear by late this afternoon; but, this only gives a few more hours of heating. Current temperatures are in the lower to mid 40s and likely will warm perhaps 5 degrees or so at most during that time. Therefore, forecast highs in the mid to upper 40s for most locations seem reasonable at this point. A few locations may get close to or reach 50 degrees, especially over northwest Alabama. Forecast thinking for tonight has not changed since the previous update. There is a low to medium chance (20-40%) of fog development this evening and overnight. Some of this may actually be freezing fog over northeast Alabama and into southern middle Tennessee as temperatures drop to freezing or just below late tonight into early Sunday morning. Overall, expect lows in the lower to mid 30s. As clouds increase once again late tonight into Sunday and as the sun rises, any fog will then dissipate. && .SHORT TERM... (Sunday through Monday) Issued at 938 AM CST Sat Dec 6 2025 The base of the aforementioned upper trough will amplify just a bit and swing over the Southeast through Monday. Additionally, a surface cold front will traverse the region Sunday night as well, with high pressure pushing into the region from the west by Monday afternoon. With this front will come low to medium chances (20-40%) of rain for all of north Alabama and southern middle Tennessee. Thunderstorms are not anticipated with this activity due to the lack of any instability. As the front pushes to the southeast early Monday morning, rain chances will taper off. Dry conditions will then return for the afternoon. A bit warmer temperatures are expected on Sunday and Sunday night, but not by too much. Highs Sunday are forecast to only reach the lower 50s due to cloud cover, with mid 30s to around 40 degree lows Sunday night. Behind the cold front will come colder air due to cold air advection from the northwest. Highs on Monday are expected to merely top out in the lower to mid 40s. Some areas in the higher terrain of northeast Alabama and southern middle Tennessee may see cooler highs, in the upper 30s to around 40 degrees. && .LONG TERM... (Monday night through Friday) Issued at 1105 PM CST Fri Dec 5 2025 Back to sub-freezing lows again Monday night with clear skies and high pressure building in. Lows in the mid 20s are expected. This intrusion of colder air should be brief, as warm air advection ahead of another front moving through the western Great Lakes early next week keeps things on the warmer side. Highs in the lower 50s should warm into the 55 to 60 degree range on Wednesday with lows warming as well into the lower to mid 30s. This front seems to have a hard time pushing into the southeast and hangs up over eastern Texas into the Ohio Valley. However, a weak pre-frontal trough axis looks to be close enough to produce a few showers over the area Wednesday night into Thursday. This weak pre-frontal trough axis may focus a bit more moisture and forcing over the area Thursday afternoon into Thursday night, before pushing east of the area. This should pull the precipitation east with it as colder and drier air moves into the area. Highs look to drop back down into the upper 30s to lower 40s again on Saturday. && .AVIATION... (00Z TAFS) Issued at 450 PM CST Sat Dec 6 2025 VFR conditions will prevail this evening underneath a clear sky. Patchy fog may develop late tonight into early Sunday morning at both terminals and have included a TEMPO to highlight the potential for localized MVFR to IFR conditions. Thereafter, VFR conditions will prevail through the remainder of the period with light southerly winds and a mostly clear sky. && .HUN WATCHES/WARNINGS/ADVISORIES... AL...None. TN...None. && $$ NEAR TERM...26 SHORT TERM....26 LONG TERM....KTW AVIATION...AMP.24 ####018008437#### FXUS65 KRIW 062254 AFDRIW Area Forecast Discussion National Weather Service Riverton WY 354 PM MST Sat Dec 6 2025 .KEY MESSAGES... - Snowfall rates will decrease across the mountains and western Wyoming through the afternoon. Lighter snow will fall at times through tonight. Continued winter travel conditions are possible, especially over mountain passes. - Wind gusts of 35 to 45 mph across the I-80 Corridor will decrease through the rest of the afternoon. However, westerly gusts of 25 to 35 mph will persist through tonight. - Another round of increased snowfall rates is expected for the western Wyoming mountains on Sunday. - Above-normal temperatures and windy conditions are expected across the area for much of the upcoming week. An active pattern will keep near-continuous snow chances for the western mountains during this time. && .UPDATE... Issued at 117 PM MST Sat Dec 6 2025 Snowfall rates are beginning to decrease across western Wyoming early this afternoon as moisture and jet support dwindle. There has been little change in additional forecast accumulation rates through today, and most of the highlights will expire at 2 PM. We'll keep the Winter Storm Warning going across the western slopes of the Bighorns through sunset. Lighter snow will then continue through tonight across the same areas. One change we're seeing in the short term is an uptick in snow potential across western Wyoming on Sunday. While midlevel heights will generally rise across the state, a quick shortwave will combine with warm air and moisture advection up the Snake River Plain to produce a period of moderate snowfall Sunday afternoon and night. As usual this will be most noted in the Tetons where guidance is now showing around a 70% chance of another 8+ inches; surrounding west- facing slopes will also be favored to see 6+ inches during this time. A short Winter Weather Advisory may be considered for the Tetons given the potential for travel impacts over Teton Pass Sunday afternoon and night. Otherwise, the gusty west wind seen across the area will decrease through the afternoon. However, wind will not shut off completely given the active northwesterly flow and another building pressure gradient for Sunday. This will keep breezy conditions for most through the weekend. && .DISCUSSION... Issued at 247 AM MST Sat Dec 6 2025 A strong, 120kt to 130kt upper level jet continues to advect moisture rich air into the Intermountain West early this morning. Wyoming is in the left-exit region of this upper level jet, a region where upper level divergence and lift is maximized. These favorable upper level dynamics combined with abundant moisture (above the climatological 90th percentile) will continue support periods of moderate to heavy snowfall across western Wyoming and the western Bighorn Mountains today. Thus, no changes have been made to the Winter Weather Advisories and Winter Storm Warnings. Additional snowfall amounts over the Teton and Gros Ventre Mountains and the Salt River and Wyoming Ranges range from 5 to 12 inches, with higher elevations seeing up to 20 inches, through the early afternoon. The snow show for the western Bighorns is expected to continue with possible (60-80% chance) snowfall rates of 1"/hour from 5AM to noon today. These high snowfall rates are partially due to favorable upsloping across the western Bighorns. Total snow accumulations of 8 to 15 inches are likely (80% chance) across the western Bighorns through sunset today. Periods of snow are also possible (30-50% chance) across the eastern Bighorn Basin through sunset. Additional snow accumulations across Jackson and Star Valleys, Yellowstone National Park, and the Upper Green River Basin range from 1 to 4 inches, with locally higher amounts across foothill areas and higher elevations of Yellowstone. Although these amounts may seem minimal, webcams across these areas show snow covered roads and reduced visibilities due to gusty winds. Because these conditions are expected to continue through the morning, the Winter Weather Advisories remain in effect. The western Wind River and Absaroka Mountains have an 60-80% chance of 8 to 15 inches through the morning. For all of western Wyoming, the periods of moderate to heavy snow should end by late morning/early afternoon as drier air begins to move in and support aloft weakens slightly (upper jet reduces speed to 80kts-100kts). The other story this morning are gusty winds across much of the area. 2AM SPC Mesoscale Analysis page shows winds of 40 to 50kts across the much of Wyoming. These winds are look to somewhat be translating down to the surface with observations showing gusts of 25 to 45 mph, with isolated gusts above 50 mph in wind prone areas. These 700mb winds are forecasted to increase to 50 to 65kts behind a weak boundary through the early afternoon. This means winds at the surface are forecast to gust 40 to 50 mph, with wind prone locations seeing gusts of or above 60 mph during this time. No wind highlights have been added given where Wyoming is in proximity to the upper level jet and a weak diurnal inversion is just strong enough to hinder full mixing. By early afternoon, mean 700mb winds decrease to 25 to 35kts across the area as the upper level jet weakens. By this time, mixing will allow these winds to translate to the surface so expect a gusty conditions through the afternoon and overnight hours, especially across the Wind River Basin, the Absarokas, and the southern half of Wyoming. There is good consensus that ridging will begin to shift into the region on Sunday and cut off the widespread abundant moisture that we have been seeing the past few days. Snow chances (40-80%) on Sunday will be confined to western Wyoming given favorable orographics. Elsewhere, a mild day can be expected with slightly above normal temperatures. A cold front is on track to traverse the area Sunday night into Monday with snow chances (60-90%) across the west. However, this cold front will do the opposite of cool us down. Mean 700mb temperatures are currently forecast between 0C and -5C Monday through at least Thursday. This reflects widespread high temperatures between 40 and 50 degrees. This is 10 to 20 degrees above normal for mid December! A weather system looks to move through the region Wednesday and with warm temperatures this means some areas would see rain as opposed to snow. As for wind, Tuesday through Thursday look to also be gusty with early signal of a 130kt upper level jet overhead. However, these temperatures and winds are subject to change given we are 3 to 6 days out. && .AVIATION /00Z TAFS THROUGH 00Z MONDAY/... Issued at 354 PM MST Sat Dec 6 2025 West of the Divide...KBPI/KJAC/KPNA/KRKS Terminals. A few lingering snow showers may move over a terminal in the first few hours of the period, but any impacts would be brief. The exception will be at KJAC, where a continued 20 to 40 percent chance of light snow occurs through the night as moisture inflow persists in the west-northwest flow aloft. The main impact from this should be low-end VFR to high-end MVFR ceilings, with occasional periods of light snow. Better chances move into the area late Sunday morning, with snow rates increasing between 17z and 19z. This also brings increased clouds to other sites. East of the Divide...KCOD/KCPR/KLND/KRIW/KWRL Terminals. Low clouds and isolated snow showers will continue from KWRL to KCPR for the first few hours of the period, and should be completely gone by about 10z. Outside these snow chances, VFR conditions prevail across the area. Winds slowly decrease through the night, with gusts again increasing by late Sunday morning. Please see the Aviation Weather Center and/or CWSU ZDV and ZLC for the latest information on icing and turbulence forecasts. && .RIW WATCHES/WARNINGS/ADVISORIES... Winter Storm Warning until 5 PM MST this afternoon for WYZ008. && $$ UPDATE...Myers DISCUSSION...Gerhardt AVIATION...Wittmann